With known crochet galloon machines it is possible to produce bands on up to six crochet needles per centimeter of working width. At most individual patterns can also be produced on eight crochet needles per centimeter, but larger amounts of band cannot be produced in this way with continuous operation.
Although it is possible to produce bands on eight or more crochet needles per centimeter of working width on Raschel looms, these machines cost six to eight times as much to purchase as a crochet galloon machine. Moreover, they have a minimum working width of 2 to 3 meters. For economical production a relatively large number of bands must be produced side by side in order to utilise the entire working width. This entails a relatively long preparation time. Raschel looms can therefore be used economically only for producing large amounts of bands. For smaller amounts it is economically preferable to use a crochet galloon machine. Such machines moreoever have a working width of only 35 to 80 centimeters.
In addition, it is possible to produce bands with eight or more threads per centimeter of width on braiding machines. However, with braiding machines the output of bands per unit of time amounts to only about one sixth of that achieved with crochet galloon machines.
With a single crochet galloon machine it is possible to replace 20 braiding machines, each with two braiding heads, or four automatic weaving machines, each with four weaving sections; this shows the economic importance of the use of crochet galloon machines.
Whereas in the production of elastic bands in crochet galloon machines the elastic threads are hooked around directly during the actual production of the band, a braiding machine must be fed with elastic threads previously covered by hooking around. In addition, a braiding machine requires for its bobbins relatively small spools which necessitate continual respooling.
A weaving process moreover does not make it possible to obtain inexpensive elastic bands, because the weaving machine must also be fed with previously covered elastic threads.
Known crochet galloon machines are however not suitable for the production of relatively large amounts of bands on more than six crochet needles, that is to say with more than six elastic threads per centimeter of width. The arrangement and the guiding of the crochet needles are not suitable for this purpose, nor are known guide needles suitable for feeding elastic threads.
In known crochet galloon machines the ends of the stems of the crochet needles are clamped fast in a clamp device on the needle bar. The free ends of the crochet needles, which project a relatively great distance, are moved to-and-fro in the comb of a knocking-over bar, which is joined to the needle bar.
The needle stems necessarily have clearance between the prongs of the needle comb. Since during the crochet operation the needle heads must intermittently project relatively far out of the needle comb, the crochet needles may in addition become laterally bent. This has the consequence that warp threads are occasionally not laid in the correct needle heads, but in neighbouring needle heads, and also that threads which are to be worked in, particularly elastic threads, are not laid in the correct gap between crochet needles, but are laid at the side of it. In such cases it is no longer possible to form perfect wales.
Because of the continual reciprocating movement inside the needle comb, the crochet needles are subject to wear. In a machine which is operated in two shifts on each working day at a rate of 800 revolutions, that is to say to-and-fro movements of the crochet needles, per minute, the crochet needles have to be replaced roughly every two months. The fact that the crochet needles are roughened by friction of steel on steel also has disagreeable consequences, since this leads to an irregular stitch pattern in the bands produced.
The present invention seeks to construct the crochet tools in a crochet galloon machine in such a manner that bands can be produced on more crochet needles per centimeter of working width than is possible in the prior art, particularly on at least ten crochet needles per centimeter of width. The crochet needles should nevertheless be suitable for working elastic threads. In addition, the crochet needles should be protected against wear.
This problem is solved by the present invention.
In contrast to the prior art, the stems of the crochet needles are no longer guided in a comb of the knocking-over bar.
On the contrary, they move reciprocatingly close above a free edge of the knocking-over bar. The crochet needles are accommodated in a clamp device, which is moved reciprocatingly with the needle bar. The needle stems are clamped down relatively far towards the needle head, so that their working regions remaining free can no longer be bent sideways to a disturbing extent. All play, such as that between the prongs of the previously known needle combs, is eliminated. (The term "working region" of a needle should be understood to mean the region on which the loops of the stitches being formed have to move to-and-fro.)
Owing to the fact that the working regions of the crochet needles no longer move to-and-fro between the prongs of a comb on the knocking-over bar, but move freely above the free edge of the knocking-over bar, there is absolutely no friction on the latter. The crochet needles have a substantially longer life, namely more than a year, as compared with two months in the example given above. Moreover, the advantageous effect is achieved that the crochet needles are not only not roughened, but on the contrary are polished by the threads being worked. It is found that the stitch pattern in the bands produced becomes more regular and cleaner in the course of the first few weeks after the installation of new crochet needles.